smtplib envía un correo electrónico de caleder

import smtplib
from email.MIMEMultipart import MIMEMultipart
from email.MIMEBase import MIMEBase
from email.MIMEText import MIMEText
from email.Utils import COMMASPACE, formatdate
from email import Encoders
import os,datetime

CRLF = "\r\n"
login = "[email protected]"
password = "yourpassword"
attendees = ["[email protected]",     "[email protected]","[email protected]"]
organizer = "ORGANIZER;CN=organiser:mailto:first"+CRLF+" @gmail.com"
fro = "nickname <[email protected]>"

ddtstart = datetime.datetime.now()
dtoff = datetime.timedelta(days = 1)
dur = datetime.timedelta(hours = 1)
ddtstart = ddtstart +dtoff
dtend = ddtstart + dur
dtstamp = datetime.datetime.now().strftime("%Y%m%dT%H%M%SZ")
dtstart = ddtstart.strftime("%Y%m%dT%H%M%SZ")
dtend = dtend.strftime("%Y%m%dT%H%M%SZ")

description = "DESCRIPTION: test invitation from pyICSParser"+CRLF
attendee = ""
for att in attendees:
    attendee += "ATTENDEE;CUTYPE=INDIVIDUAL;ROLE=REQ-    PARTICIPANT;PARTSTAT=ACCEPTED;RSVP=TRUE"+CRLF+" ;CN="+att+";X-NUM-GUESTS=0:"+CRLF+" mailto:"+att+CRLF
ical = "BEGIN:VCALENDAR"+CRLF+"PRODID:pyICSParser"+CRLF+"VERSION:2.0"+CRLF+"CALSCALE:GREGORIAN"+CRLF
ical+="METHOD:REQUEST"+CRLF+"BEGIN:VEVENT"+CRLF+"DTSTART:"+dtstart+CRLF+"DTEND:"+dtend+CRLF+"DTSTAMP:"+dtstamp+CRLF+organizer+CRLF
ical+= "UID:FIXMEUID"+dtstamp+CRLF
ical+= attendee+"CREATED:"+dtstamp+CRLF+description+"LAST-MODIFIED:"+dtstamp+CRLF+"LOCATION:"+CRLF+"SEQUENCE:0"+CRLF+"STATUS:CONFIRMED"+CRLF
ical+= "SUMMARY:test "+ddtstart.strftime("%Y%m%d @ %H:%M")+CRLF+"TRANSP:OPAQUE"+CRLF+"END:VEVENT"+CRLF+"END:VCALENDAR"+CRLF

eml_body = "Email body visible in the invite of outlook and outlook.com but not google calendar"
eml_body_bin = "This is the email body in binary - two steps"
msg = MIMEMultipart('mixed')
msg['Reply-To']=fro
msg['Date'] = formatdate(localtime=True)
msg['Subject'] = "pyICSParser invite"+dtstart
msg['From'] = fro
msg['To'] = ",".join(attendees)

part_email = MIMEText(eml_body,"html")
part_cal = MIMEText(ical,'calendar;method=REQUEST')

msgAlternative = MIMEMultipart('alternative')
msg.attach(msgAlternative)

ical_atch = MIMEBase('application/ics',' ;name="%s"'%("invite.ics"))
ical_atch.set_payload(ical)
Encoders.encode_base64(ical_atch)
ical_atch.add_header('Content-Disposition', 'attachment; filename="%s"'%("invite.ics"))

eml_atch = MIMEBase('text/plain','')
Encoders.encode_base64(eml_atch)
eml_atch.add_header('Content-Transfer-Encoding', "")

msgAlternative.attach(part_email)
msgAlternative.attach(part_cal)

mailServer = smtplib.SMTP('smtp.gmail.com', 587)
mailServer.ehlo()
mailServer.starttls()
mailServer.ehlo()
mailServer.login(login, password)
mailServer.sendmail(fro, attendees, msg.as_string())
mailServer.close()
py_hacker